https://djsumdog.com/objects/ec081cf4-ef20-42cb-8f8a-eaa2c214de19
Appears that the proof of infringing intent was just unit tests meant to ensure that ytdl works. It might be possible for a quality legal team to sue #RIAA and win a declaration of non-infringement. That said, I've not heard of any foundations stepping up and offering legal assistance, so it probably isn't going to happen.
Warning, though. Someone else mentioned that Nitter, Invidio.us, and similar software are probably next. Suggest downloading the repos of any desired "use corpocentric site without logging into said site" software.